"The Art of Structural Design" isn't the first book to cover these four heroic Swiss structural engineers. Billington has written previously and extensively on Maillart, and there are good books available on Menn and Isler. What makes it remarkable, however, is the particular angle it takes.
The meat of the book discusses these engineers' major works, from Ammann's George Washington Bridge through to Menn's Sunniberg masterpiece. But throughout, the focus isn't just on what brought these structures to the level of art, but on how the engineers' philosophies blended technology and aesthetics, and on where those philosophies came from in the first place.
There are two chapters on their teachers, Wilhelm Ritter and Pierre Lardy, which make clear the key influence that a good educator can have. My experience is that such people are few and far between, and this is to engineering's great loss. Billington's insightful analysis extends to poring over old lecture notes, and I'd think few intelligent engineering students wouldn't wish that those were their own notes.
As such, this is a book that could do with being far more widely read, both by engineering students and educators. It's well-illustrated throughout, and provides engineers with the aspirational figures so often lacking. Although the technical content is fairly light (with the general reader in mind), there's enough to see how only a synthesis of analytical depth with design flair can lead to the very best structural work.